It& #39;s tough to separate the performance of receivers and the coverage unit from that of the quarterback, when grading players.

I& #39;d imagine this relationship lends to both the importance and instability of coverage grades. https://twitter.com/adrian_stats/status/1311089683565285376">https://twitter.com/adrian_st...

For those unaware, PFF coverage grade is highly associated with good team results. And while it does predict future team results a bit, it& #39;s still relatively unstable. This may be partly because coverage players appear to grade worse when playing against better QBs.

Assessing defensive play in a meaningful way is really, really hard. Comprehensive grades are probably still the best resource we have right now for assessing performance in coverage. But there& #39;s still room for improvement.